CAIE A Level 9702

Physics 2022 · May/June

8 Questions Q&A Available

Questions & Model Answers 8 Qs

Short Answer 1 mark

The brightness of some stars varies regularly. These stars are called variable stars. Fig. 2.1 shows the variation of luminosity with time for a variable star. luminosity period time A student determines the period T and mean luminosity L of the star. The student repeats the process for different variable stars. It is suggested that L and T are related by the equation L = SKT where S is the luminosity of the Sun, and a and K are constants. gradient =

Q2(b)

Short Answer 2 marks

Values of T and L are given in Table 2.1. Table 2.1 T / days L / 10 W lg (T / days) lg (L / 10 22 2.9 ± 0.2 32 4.9 ± 0.2 42 6.9 ± 0.2 54 9.8 ± 0.2 78 16 ± 2 97 21 ± 2 Calculate and record values of lg (T / days) and lg (L / 10 W) in Table 2.1. Include the absolute uncertainties in lg (L / 10 W).

Q2(c)

Short Answer 2 marks

(i) Plot a graph of lg (L / 10 W) against lg (T / days). Include error bars for lg (L / 10 W).

Q2(ii)

Short Answer 2 marks

Draw the straight line of best fit and a worst acceptable straight line on your graph. Label both lines.

Q2(iii)

Short Answer 1 mark

Determine the gradient of the line of best fit. Include the absolute uncertainty in your answer. gradient = [2] 0.4 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 lg (L / 10 lg (T / days) answer.

Q2(d)

Short Answer 1 mark

Using your answers to

Q2(d)(iv)

Short Answer 1 mark

, determine the values of a and K. Include the absolute uncertainties in your values. You need not be concerned with units. Data: S = 3.85 × 10 a = K =

Q2(e)

Short Answer 1 mark

A variable star has a period of 5.0 days. Determine the luminosity L of this star. L = W [1] [Total: 15] Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series.

Paper Details

Board	CAIE
Level	A Level
Subject	Physics
Code	`9702`
Year	2022
Session	May/June
Q&A	8 questions

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